Box making apparatus



May 24, 1960 E. c. CLEMENT Box MAKING APPARATUS Filed Jan. 3, 1956 t! !lA M .H. v 'w MWA QW w m w] J Z r A j z .W15 N W M I/ L M r. .m4 MW NW@wl A H H. m 1||-l-. n. if MN NMA f FE-:Ezzz-: E .F

United States Patent r BOX MAKING APPARATUS Ernest C. Clement, 315 N.Euclid, lOak Park, Ill.

Filed Jan. 3, 1956, Ser. No. 556,950

6 Claims. (Cl. 74-26) This invention relates Vto apparatus vfor makingboxes of the paperboard type. lIn particular the invention deals withapparatus for impartingreciprocative movement to a box forming plunger.

A,The apparatus of this invention advantageously may be used, forexample, with the box making die shown in my Ycor-pending applicationentitled Box Making Die, Serial No. 424,149, tiled April 19, 1954. Thedie there shown is characterized by extreme flexibility as to the sizesof boxes which may be formed thereby. 'Ihe present apparatuscontemplates a series of diierent sized plungers which cooperates withthe adjustable die shown in the prior application in order to provide asingle machine capable of forming boxes in an extremely wide range ofsizes and at high speed. Such a machine is here called a multi-purposemachine. i

As more fully set forthin my prior application, boxes made withapparatus of this type are constructed Vof paperboard which is formed todesired shape Yin theV apparatus and then glued at suitable points toretain the shape.

Generally speaking, present machines used in the forming and gluing ofpaperboard boxes employ two common elements, a plunger which conforms tothe inside dimensions of the box to be formed, and a die which forms apreviously ilat box blank around the plunger. Ordinarily the die isstationary, and a at box blank is brought to rest either above or belowthe die. The plunger then enters the die from above or below, as thecase may be, and the box blank takes the form of the plunger from theaction of the die which conforms to the outside 'dimensions of the boxto be formed.

A machine designed to make abox of a single size only, here called asingle purpose machine, is so constructed that the length of stroke ofthe plungeris appropriate to the vertical dimension' of the box. Withlsuch a machine the maximum production speed which may be obtainedusually is determined bythe length of the plunger stroke required toform the box and the inertia factors of the plunger itself inacceleration and deceleration.

Since portions of the box are glued together, pressure must be exertedon these portions after the plunger has entered the die and impartedproper shape to the box. To permit the application of this pressure, itis necessary to provide a dwell at the extended end of the plungerstroke. Therefore the plunger may not be driven by a constant speedcrank which resultsY in a simple sine curve type of motion having nodwell to accommodate the pressure requirement. n

At the withdrawn end of the plunger stroke the plunger must beseparatedjfrom the die a suicient length of time to permit thepositioning of a box blank in effective relation with the die. If a sinecurve type of motion were applied to the plunger in this withdrawnportion of the stroke, the length of the stroke would be excessive inorder to permit the positioning of a blank on the die, or the length oftime allotted to the blank positioning step would be excessively brief.Therefore a sine curve type of motion likewise is not suitable for'theplunger at the withdrawn end of its stroke.

In general, prior single purpose machines have used a 2,931,536 PatentedMay 24, 1960 cam to impart proper motion to the plunger, the cam -beingdesigned to provide dwells at the extended and withdrawn ends of thestroke to permit glue pressure application at the extended end of thestroke and to permit positioning of the blank at the withdrawn end ofthe stroke. With a carefully designed cam it is possible to provide asinglefpurpose machine which operates at the maximum possible speedwithin the limitations imposed by required stroke length and the inertiafactors of the plunger and associated drive elements.

The present apparatus, however, does not contemplate a single purposemachine. Rather it contemplates a machine capable of making boxes in awide range of sizes, a multi-purpose machine. A multi-purpose machineconstructed in accordance with the prior art presents a serious designdilemma. It is, of course, advantageous in any automatic box makingmachine that the productivity be a maximum at all times, since theprimary purpose of automatic equipment is to increase production.

Some multi-purpose machines appear in the prior art, and these machinesemploy a cam, as described above, to impart the desired motion,including the aforesaid dweils, to the plunger. In such a machine thelength of plunger stroke necessarily is determined by the verticaldimension of the maximum sized box that can be made on the machine. Thespeed or productivity of themachine is thereby established as a functionof the inertia factors of the plunger in acceleration and decelerationfor the set stroke length. When the machine is usedfor a box of smaller'or minimum vertical dimension, the same factors remain in control, andthe maximum speed attained on the smaller 4box still is a function ofthe limitations which apply to the largest box. The result is either asevere limitation on speed, or a severe limitation on the range of boxsizes that can be handled in the machine, or both.

To solve the design dilemma described above, the present inventionutilizes an adjustable-length crank which provides variability in thelength of the plunger stroke. This permits the stroke length to bevaried advantageously according to the requirements of a particular boxsize. An adjustable crank alone, however, does not solve the problem forthe reason, mentioned above, that a constant speed crank provides a sinecurve type of motion wherein the required dwells are lacking.

In addition to the adjustable length crank the invention employs a cam,here called a rate cam, which, as will be seen, is eiective to changethe rate at which the crank moves during various parts of its rotarycycle. The crank rate is adjusted to zero at the extended and withdrawnends of the plunger stroke to provide the required dwells, and thelength of the crank then eas-ily can -be adjusted to provide optimumstroke lengths for various box sizes.

The motion provided by the present rate cam requires differentiationbefore it provides the desired result in controlling the motion of thecrank. This differentiation is obtained by means of a dilierentialsystem in which a constant speed input is modied by the varying speedmovement provided by the rate cam, the output motion of the diiferentialsystem being proper for the crank which drives the plunger.

Other objects, advantages and features of the invention will be apparentas the description proceeds, reference being had to the accompanyingdrawing wherein one form of the invention is shown. It is to beunderstood that the description and drawing are illustrative onlyVassess@ Fig. 2. is a plan view of a portion of the apparatus showing thedifferential system here employed.

Referring now to the drawing, apparatus embodying the invention includesa box forming plunger 5. The precise shape of plunger S is not a featureof the invenlion, but ordinarily such a plunger in plan View is squareor rectangular. Since the external dimensions of plunger conform to theinternal dimensions of a box to be formed thereby, a multi-purposemachine embodying this apparatus utilizes a series of different sizedplungers 5, there being one plunger for each box size.

As previously mentioned, a plunger 5 cooperates with a box making diesuch, for example, as the adjustable die shown in my aforesaidapplication Serial No. 424,149.

Plunger 5 is carried by a slider 6 arranged for reciprocative movementin one or more bearings 7. A plunger 5 is detachably mounted on slider 6as indicated at S so the respective plungers 5 readily may beinterchanged.

Slider 6 and associated plunger 5 are driven by means of a rotatingcrank 19 carried on a crankshaft 11 which is rotated at varying speed,as will be seen. The varying speed of crankshaft 11 is such that twosubstantial-duration dwells occur in each revolution of the shaft, thusto provide the required plunger dwells at the extended and withdrawnends of the plunger stroke.

A suitable driving connection such as a link 12 extends between crank 1Gand slider 6, link 12 being pivoted at its ends to the crank and slider.The effective length of crank is adjustable to vary the stroke length ofplunger S, and as here shown, crank 1G has an elongated slot 13 near itsfree end. Suitable means 14 on link 12 or the crank pin permit theadjustment of the pivoted end of link 12 along crank 16 in a lengthwisemanner. By this adjustment the stroke length of plunger 5 may be varied`and set to be a minimum for each different sized box. As previouslymentioned when stroke length is a minimum, machine speed andproductivity can be a maximum.

Apparatus for driving crankshaft 11 at the desired varying speed nowwill be described, it being understood that crankshaft 11 makes onecomplete revolution or cycle during the formation of a single box. Thus,crankshaft 11 may be termed a cycle shaft which rotates at varying speedwith two dwells per revolution.

Apparatus embodying the invention includes two other shafts which alsomay be termed cycle shafts in that they rotate through one revolutionfor each cycle of box formation. These two shafts, unlike crankshaft 11,rotate at constant speed during a given run of machine operation. Thisspeed, yhowever, may be varied as between successive runs depending onthe size of the box being formed. Such speed will be relatively slow forthe larger boxes and relatively fast for the smaller boxes, these boxsizes, of course, being a measure of the required stroke length andinertia of the plunger.

One of these two shafts is a constant speed first shaft 20 and the otheris a constant speed second shaft 21. As previously mentioned, shafts 20and 21 make one revolution or cycle at constant speed for each box.

Shafts 20 and 21 are driven in any suitable manner as by sprockets 22and 23 respectively keyed thereon, the sprockets being engaged by anendless chain 24 driven by a driving sprocket 25 carried on a drivingshaft 26. Since sprockets 22 and 23 are identical in size, shafts 20 and21 are driven at the same speed by chain 24.

A rate cam 30, keyed on constant speed first shaft 20, is engaged by acam follower 31 which is carried by an arm 32 pivoted on a fixed shaft33. Thus, cam follower 31 oscillates in accordance with the shape ofrate cam 30. A link 35, pivoted at one end to cam follower 31, has itsother end pivoted at 36 t0 an eccentric point on a first sprocket 37which is carried on a shaft 38. First sprocket 37 thus is driven in anoscillating manner by link 35 which in turn is connected to oscillatingcam follower 31.

Referring again to constant speed second shaft 21, a second sprocket 40is journalled for rotation on shaft 21. Suitable means such as endlesschain 41 interconnects first sprocket 37 and second sprocket 40 so thatthe latter oscillates in synehronism with the former. Second sprocket 40could, of course, be driven directly from cam follower 31 if desired. Itwill be remembered that second shaft Z1 on which sprocket 40 isjournalled rotates at constant speed through one revolution for each boxmaking cycle.

A three-gear differential system, generally designated 45 in Fig. 2, isdisposed in operative relation with second sprocket 40 and constantspeed second shaft 21.

In Vthe form of the invention shown, differential system 45 includes anidler miter gear 46 journalled for rotation on a stub shaft 47 extendingfrom hub 48 (Fig. 2) of second sprocket 40. As shown in Fig. 1, secondsprocket 40 is cut away at 49 to accommodate stub shaft 47 and idlermiter gear 46. The axis of idler miter gear 46 thus extends normal toconstant speed second shaft 21, and this axis oscillates back and forthwith second sprocket 40 through a partial revolution.

An input miter gear 50 (Fig. 2), keyed to second shaft 21, rotates atconstant speed with shaft 21. Input miter gear 50 meshes with idlermiter gear 46, as shown in Fig. 2.

An output miter gear S2, best shown in Fig. 2, is journalled on secondshaft 21 in engagement with idler miter gear 46. The instantaneous speedof rotation of output miter gear 52 is a function of the instantaneousspeeds of idler miter gear 46 and input miter gear 50, and this outputspeed varies because of the varying speed provided by the oscillationsof idler miter gear 46.

With proper design of rate cam 30, the varying-speed rotary motiondeveloped by output miter gear 52 is suitable for driving plunger 5 bymeans of a simple crank. Although a crank effectively could be mountedon output miter gear S2, the present embodiment of the inventioncontemplates a direct driving connection extending between output idlergear 52 and the aforesaid crankshaft 11.

As here shown, a sprocket 55, associated with output miter gear 52,drives an endless chain 56 which engages and drives a sprocket 57 keyedto crankshaft 11. Thus crankshaft 11 is driven with the same varyingspeed as that of output miter gear 52.

As previously described, the varying speed of crankshaft 11 iscommunicated to plunger 5 by means of adinstable-length crank 10 andpivoted link 12, the latter engaging slider 6 which reciprocates on astraight line and carries plunger 5.

The instantaneous speeds of the respective miter gears of theillustrated differential system are related as follows:

Y is the uniform rate of rotation of input miter gear 50,

and

Z the instantaneous rate at which idler miter gear 46 oscillates aroundsecond shaft 21.

A more general form of Equation 1 is:

X EY Z-T'* (2) where:

E is the ratio of the number of teeth on input miter gear 50 to thenumber of teeth on output miter gear 52, the other variables being asdescribed above. The ratio E has negative sense when there isan oddnumber Of miter gears, as here, and positive sense when there is an evennumber. Since gears 50 and 52 have the same number of teeth in theillustrated differential system the ratio E is 1).

The directions of rotation of constant speed shafts 20 and 21 areimmaterial so long as rate cam 30 is shaped properly. As indicated bythe above equations, if the two shafts 20 and 21 rotate in the samedirection, then crank turns in one direction, but if the two shaftsrotate in opposite directions, then crank 10 turns in the otherdirection.

When rate cam 30 imparts proper oscillatory motion to second sprocket40, idler miter gear 46 oscillates in such manner that output miter gear52 has the proper two dwell periods for desired plunger operation.

By way of example, during each 360 cycle of constant speeds shafts 20and 21, 90 each may be allocated to the dwells at the extended andwithdrawn ends of the stroke, and 90 each may be allocated to theoutward and inward strokes.

The dwell pattern having been established by rate cam 30 to the mostadvantageous form, variable-length crank 10 may be adjusted to provide alength of stroke most appropriate to the particular box being formed. Inthis manner the maximum speed of the machine on a particular box may bethat which is most advantageous for that box, and the average speed ofthe machine for all boxes is raised considerably from that which hasbeen possible on prior multi-purpose machines.

One further feature in connection with adjusting the plunger stroke foroptimum length needs to be mentioned. The die element with which theplunger cooperates has a fixed position in the machine, and thepaperboard box blank is fed to a xed positionr in relation to the die.Therefore it is desirable that the plunger have a teminal position atthe withdrawn end of the stroke that is substantially the same for allbox sizes and stroke lengths. In other Words, the stroke lengthvariation provided by the apparatus is reflected in the terminalposition of the plunger at the extended end of the stroke.

The substantially uniform terminal position at the Withdrawn end of theplunger stroke is provided by suitable adjustment of the drivingconnection between crank 10 and slider 6. As here shown, an elongatedslot 60 is provided in slider 6 and cooperating adjustable means 61establishes proper relationship between link 12 and a desired point onslider 6 along slot 60. Thus an adjustment may be made on slider 6 tocompensate for the stroke-length adjustment made on crank 10 in order topreserve the proper terminal position of the plunger at the withdrawnend of the stroke.

In practice, a multi-purpose machine embodying the present invention iscapable of a range of box sizes which is roughly double that of anycomparable prior multipurpose machine, and the productivity rate on anyparticular size is approximately equal to that attained by anycomparable single purpose machine, such productivity rate beingconsiderably greater than that possible on prior multi-purpose machines.

From the above description it is thought that the construction andadvantages of my invention will be readily apparent to those skilled inthe art. Various changes in detail may be made without departing fromthe spirit or losing the advantages of the invention.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. Apparatus for imparting reciprocative movement to a box makingplunger wherein a substantial dwell period is provided at eachl end ofthe plunger stroke, said apparatus comprising a constant speed firstshaft, a rate cam keyed on said first shaft, a cam follower engagingsaid cam, an oscillating first sprocket driven by said cam followerwhereby said first sprocket has one cycle of oscillation for each rotarycycle of said first shaft, a constant speed second shaft, a drive meansimparting a constant Speed to said rst and second shafts, a secondsprocket journalled on said second shaft, means interconnecting saidfirst and second sprockets for synchronous oscillation, an idler mitergear carried by said second sprocket on an axis normal to said secondshaft, an input miter gear keyed to said second shaft and engaging saididler miter gear, an output miter gear journalled on said second shaftand engaging said idler miter gear, a crank, said output miter geardrivingly connected to said crank, and a driving connection between saidcrank and said plunger.

2. The combination of claim 1 wherein said crank is adjustable in lengthwhereby the total stroke of said plunger may be varied to be a minimumfor each of various different effective strokes.

3. Apparatus for imparting reciprocative movement to v a box makingplunger wherein a substantial dwell period is provided at each end ofthe plunger stroke, said apparatus comprising a constant speed inputdifferential gear which rotates one revolution per reciprocative cycleof said plunger, a drive means imparting a constant speed to said inputdiiferential gear, an idler diierential gear engaging said inputdifferential gear, a shaft on which said idler differential gear ismounted for rotation, said shaft having a right angle relation with theaxis of said input diierential gear and mounted for radial oscillationon said axis as a center, means imparting continuous radial oscillationto said shaft at a rate whereby there is one cycle of oscillation perrevolution of said drive means, a varying speed output differential gearengaging said idler differential gear, a crank, said output differentialgear drivingly connected to said crank, and a driving connection betweensaid crank and said plunger.

4. The combination of claim 3 wherein said crank is adjustable in lengthwhereby the total stroke of said plunger may be varied to be a minimumfor each of various different effective strokes.

5. Apparatus for imparting reciprocative movement to a box makingplunger wherein a substantial dwell period is provided at each end ofthe plunger stroke, said apparatus comprising a constant speed firstshaft, a rate cam keyed on said first shaft, a carn follower engagingsaid cam and driven thereby in an oscillatory manner whereby said camfollower has one cycle of oscillation for each rotary cycle of saidfirst shaft, a constant speed second shaft, a drive means imparting aconstant speed to said iirst and second shafts, a sprocket journalled onsaid second shaft, means interconnecting said cam follower and saidsprocket for synchronous oscillation, an idler miter gear carried bysaid sprocket on an axis normal to said second shaft, an input mitergear keyed to said second shaft and engaging said idler miter gear, anoutput miter gear journalled on said second shaft and engaging saididler miter gear, a crank, said output miter gear drivingly connected tosaid crank, and means connecting said crank to said plunger.

6. The combination of claim 5 wherein said crank is adjustable in lengthwhereby the total stroke of said plunger may be varied to be a minimumfor each of various different eifective strokes and wherein said meansconnecting said crank to said plunger is adjustable to provide apredetermined terminal plunger position at the withdrawn end of thestroke regardless of stroke length.

References Cited in the file of this patent UNITED STATES PATENTS224,767 Britain Feb. 24, 1880 242,275 Conner May 31, 1881 945,197Robertson Jan. 4, 1910 1,295,800 Schneider Feb. 25, 1919 1,946,506Swanson et al Feb. 13, 1934 2,243,352 Macdonald et al. May 27, 19412,301,543 Hlavaty Nov. 10, 1942 2,470,766 Durning May 24, 1949 FOREIGNPATENTS 213,597 Great Britain Oct. 30,1924

